Truffle: Improved support for "probing" AST nodes: - Node.isSafelyReplacaeableBy(Node) checks in advance if Node.replace(Node) would be unsafe (crash the VM). - Hoist Probe() from language imlementations into Node; now completely language agnostic. - Language implementations support probing by implementing Node.isInstrumentable() and Node.createWrapperNode() - Node.Probe() throws ProbeException (without side effects) if the probe fails. -- ProbeException contains an instance of ProbeFailure that diagnoses the failure in detail - Additional measures to prevent instrumentation from being applied to internal InstrumentationNodes. - Promote ProbeListener to top level interface and add a default implementation

/*
 * This test verifies the compilation threshold property.
 */
function test() {
}  

function main() {  
    /* TODO disableSplitting is required because otherwise it needs more calls to warm up. This still needs to be fixed. */
    disableSplitting(test); 
    threshold = getOption("TruffleCompilationThreshold");
    i = 0;
    while (i < threshold -1) {
        test();
        i = i + 1;
    }
    assertFalse(isOptimized(waitForOptimization(test)));
    test();                         // triggers compilation
    assertTrue(isOptimized(waitForOptimization(test)));
}